Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) is a procedure in which peritoneal surface tumors are removed followed by infusion of a heated chemotherapeutic solution into the abdominal cavity. This procedure is typically 6-10 hours in duration and is accompanied by significant fluid shifts and hemodynamic changes. Patients frequently receive between 10 and 20 liters of fluid during the procedure. Patients undergoing cytoreductive surgery with HIPEC also experience vasodilatation and a hyperdynamic cardiac state during the hyperthermic period. Classically, the need for volume replacement has been guided by following a patient's urine output (UOP) and the use of central venous pressure (CVP). However, several studies have shown that CVP is not a reliable measure of intravascular fluid status.